instmctions): CORE B: Cell and Tissue Acquisition Core Abstract: The purpose of this Core is to provide cellular material, DNA/RNA, serum, plasma, cell lines pathology specimens as available, and other materials to each investigator and to provide flow cytometry and cell sorting services in a timely fashion. We have an active laboratory that is well versed in cell isolation, storage, generation of cell lines, cell analyses, RNA and DNA isolation. While fresh samples are often needed for work in the Program project, this Core has ample storage facilities in liquid nitrogen and a log system for these materials so that they can be retrieved for later studies as needed. There is also an active flow cytometry facility with state ofthe art equipment for analysis and sorting. For tissue specimens there are also three sources of materials - the out patient offices, the operating rooms for surgical procedures and the endoscopy suite for gastrointestinal endoscopic biopsies. The P.l. (Dr. Mayer) has been working closely with Dr. Harpaz in Pathology, to secure surgical specimens for research. This has facilitated access to such tissues as well as input from the pathologists in terms of histologic analyses. This cell isolation, phenotyping, cell culture and tissue Core serves to support Projects 1-4 in this ongoing Program Project.